Effects of Be-metal (Fe and Nb) co-precipitation on 10Be analysis by accelerator mass spectrometry at ASTER (CEREGE-Aix-en-Provence-France)

Prior AMS measurements at ASTER, beryllium oxides (BeO) samples are mixed with metal conducting powder and packed in copper target to improve ionisation efficiency. Several tests were performed at LN2C, the National Laboratory of Cosmogenic Nuclides in France, to monitor the behaviour of 9 Be current - including intensity, stability and longer-lived ion beam current performance - for various Nb (or Fe)/Be ratios that can sustain measurements lasting up to one hour under routine AMS conditions. From these tests, setting an amount of 2.5 mg of niobium with variable 9 Be carrier additions from 0.15 to 0.3 mg shows no variation in 9 Be current during for one hour.